Field of the Invention
The present disclosure relates to an organic light emitting display device. More particularly, the present disclosure relates to an organic light emitting display device with improved efficiency and lifetime.
Discussion of the Related Art
Image displays, used for displaying a variety of information on the screen, are one of the core technologies of the information and communication era. Such image displays have been developed to be thinner, lighter, and more portable, and furthermore to have high performance With the development of the information society, various demands for display devices are on the rise. To meet these demands, research on panel displays such as liquid crystal displays (LCD), plasma display panels (PDP), electroluminescent displays (ELD), field emission displays (FED), organic light emitting diodes (OLED), etc. is actively under way.
Among these types of flat panel displays, OLED devices are advantageous in that they can be fabricated on a flexible substrate such as plastic, operate at a low voltage of 10 V or less, have lower power consumption, and deliver vivid color reproduction, as compared with plasma display panels or inorganic light emitting displays. Also, the organic light emitting display devices are spotlighted as next-generation display devices that provide rich colors for its ability to render full color images using three colors: red, green, and blue.
An organic light emitting display device can be formed by sequentially stacking an anode, a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer, and a cathode. An exciton is formed by the recombination of electrons and holes injected from the two electrodes, causing luminescent materials to emit fluorescent or phosphorescent light. The light emitting layer comprises a host and one or more dopants, or comprises two or more hosts and a dopant. The hole injection layer and the hole transport layer inject electrons from the anode into the light emitting layer, and the electron transport layer and the electron injection layer inject electrons from the cathode into the light emitting layer.
The lifetime and efficiency of the organic light emitting display device are affected by the material used and its stacked structure. In this regard, there are ongoing studies to improve the lifetime and efficiency of organic light emitting display devices.